1. Field of the Invention
The invention relates to a method for manufacturing a catheter having an expandable member, which is for use in kyphoplasty.
2. Description of the Related Art
Patients with osteoporosis, and especially aged patients often experience severe pain at the back or waist area after being subjected to even a small impact. This is generally caused due to fracture, or compression fracture, which means that the weakened spinal bone is collapsed upon inflicted by the impact. Such pains are generally treated with vetebroplasty such as kyphoplasty.
The kyphoplasty is generally carried out in the following steps. First, a void is created with a spacer which is placed within a cannular inserted into an interior of a spinal bone, and a catheter having an expandable member is inserted into the spinal bone through the interior of the cannular. A cylinder device, which is connected to the catheter having expandable member, is then operated to expand the expandable member so that the body of the spinal bone is returned to the original form. Next, bone cement is injected into the void within the spinal bone which is created in accordance with the expansion of the expandable member. As a result, the spinal bone is restored to the original form.
FIG. 1 is a schematic view illustrating an appearance of a conventional expandable member of a catheter.
Referring to FIG. 1, the catheter having expandable member for use in kyphoplasty may have an undesirable deformation during shaping thereof. That is, in the conventional manufacturing process involving deposition and shaping of a first end 511 of the expandable member 510 with a first end of a second tube (not illustrated) formed within a first tube 520, the first end 511 of the expandable member 510 sometimes protrudes or overlaps with the second tube. Such deformation is undesirable, since when the catheter 500 having expandable member is inserted into the spinal bone in kyphoplasty, the protruding first end 511 of the expandable member 510 easily touches or is blocked by an inner wall of the void which is created by the spacer to receive the catheter 500 having expandable member. Therefore, to overcome the above-mentioned potential problem and ensure that the catheter 500 with the expandable member is inserted accurately, the void has to be created larger than necessary.
Furthermore, after the void is ensured by the expansion of the expandable member 510, the expandable member 510 on the first end of the catheter 500 having expandable member, which is thickened due to overlapping with the second tube within the first tube 520, can be blocked by the cannular while the catheter 500 is removed from the cannular.
Further, it is necessary that the expandable member 510 of the catheter 500 is made from a substance with effective hardness and elongation to be used in kyphoplasty. To be specific, high hardness and elongation are particularly necessary, which can endure sufficient supply of pressure, and at the same time, can permit sufficient expansion without having breakage, to ensure that the expandable member 510 expands the collapsed or dying bones. Conventionally, expandable members have been generally made from a substance containing duralyn which is a nylon family or silicone, and some polyurethane family, but these substances could not provide sufficient hardness and elongation to meet the need to expand the bones.